The Demciflex filters offer a non-ferrous version that basically includes a thin magnetic layer with adhesive on one side so you can apply their filters to non-ferrous materials (wood, plastic). It's indiscernible from the standard ferrous version (I think it only adds a fraction of a mm of thickness) and sticks very well.
To clarify: the non-ferrous product includes an adhesive magnetic strip so the filters can still be removed easily and re-installed onto the magnetic strip.
Oh. Well, problem solved then. Back to my regularly scheduled fawning over the wood panels. Thanks for the tip; I was imagining a world in which I'd have to route out a small channel to embed a thin strip of metal. At the same time, I was considering how much less structural rigidity the wooden panel would have when thrown in a travel case.